1. Field of the Invention
The invention relates generally to the semiconductor power devices. More particularly, this invention relates to configurations and methods for manufacturing of new and improved edge terminations for high voltage (HV) devices for improved reliability and to reduce the areas occupied by the termination areas while maintaining high breakdown voltages.
2. Description of the Prior Art
Conventional floating guard rings in the termination area are not sufficient to sustain high breakdown voltages for high-voltage (HV) devices that have heavily doped N regions 110, e.g., doping concentration of 1016 dopants/cm3, of about two to five microns in depth below the top surface of the substrate 105 as that shown in FIG. 1. The N-charge in the heavily doped region 110 is too high and the floating guard rings, which are P type doped regions implanted in the heavily doped N region, need charge compensation in order to sustain a higher breakdown voltage in the termination area. The conventional edge termination designs with voltage drop in the oxide lining the trench are not effective in resolving the problems due to the facts that such edge termination can only sustain a breakdown voltage up to approximately 100 volts. The lower breakdown voltage of approximately 100 volts is caused by the gross field crowding effects under the trench. The low breakdown voltage at the edge termination will limit the applications of the high-voltage (HV) devices when a higher voltage operational requirement is necessary.
Therefore, a need still exists in the art of power semiconductor device design and manufacture to provide new and improved configurations of the edge termination such that the above discussed problems and limitations can be resolved.